1. Field of the Invention
This invention relates to improvements in the rip proof screen for an odor preventing, disposable, sorbent pad-liner for an animal litter unit, and more particularly to a non-woven screen for use in combination with a sorbent padding, a liquid impermeable liner, a litter container and litter.
2. Brief Description of the Prior Art
Many domestic animals frequently use litter boxes for the elimination of body wastes. The boxes are usually filled with various kinds of sorbent granular materials such as sand, cat litter and the like, and must be periodically emptied and cleaned, which are somewhat objectionable tasks, since the sorbent granular material must be replaced and the boxes cleaned each time.
Cats, the most frequent users of litter boxes, present a further problem in that the urine of the feline has the most severe tendency to produce a pervasive odor problem. Apparently, cat urine contains the highest content of urea which, when allowed to stand for any length of time in any litter material, releases an ammonia odor. In any event it is the odor associated with cat urine which is one of the most objectionable factors in the ownership of a cat.
In order to eliminate the odor caused by cat urine, the litter box must be changed frequently, this being an expensive, laborious and messy job.
Many patents have issued on devices for the indoor use by cats, such as U.S. Pat. No. 3,233,588. The invention disclosed in this patent employs the use of a screen which is placed on top of the cat litter. This patent does ease the problem of disposing of animal excrement, by merely lifting the screen and disposing of the feces lying on top. It does not however, contend with the problem of the odor created by the urine. The unit must be periodically emptied of its sorbent granules and thus only partly contents with the elimination of the mess and labor involved. U.S. Pat. No. 3,809,013 is similar, except that a stack of liners is placed under the litter. When the litter becomes soiled, the liner is lifted, the litter filters through screen covered holes in the center of the liner and the litter is reused with the next liner. Again, the excrement is disposed of neatly, however the odor problem remains.
U.S. Pat. No. 3,284,273 discloses an absorbent pad which can be used in combination with animals. Although this pad does contain absorbent capabilities, the odor from the urine of the animal is trapped, much as in the standard cat litter. The pad is not designed for repetitive, long term use in a cat box but rather to retain the urine in a disposable pad, by mopping up pools of urine left on floors or in cages, etc.
U.S. Pat. No. 3,476,083 discloses the use of deodorizing substances which are placed in the bottom of the receptacle. A screen is placed a short distance above, on which lies the standard kitty litter. The upper compartment receives the solid and liquid excreta, retains the solids and absorbs the bulk of the liquid allowing the excess liquids to drain through to the lower compartment. Although providing some neutralizing of the ammonia odor by deodorizing the urine which cannot be absorbed by the litter, it does not provide an effective means for deodorizing the bulk of the urine which has been trapped in the litter. The disposal of all the litter creates a substantial expense to the owner and the cleaning of the lower compartment would be unpleasantly laborious and rather messy. The spilling of the deodorizing substances (lime is suggested) would be objectionable as well as possibly harmful to the person handling the container if by chance some of the chemical substance was to come in contact with the skin.
U.S. Pat. No. 3,752,121, Brazzell, discloses a tray which holds a absorbent mat covered with artificial grass. "Below the artificial grass 31 and its backing sheet 32 there is provided a liquid absorbing pad 33 which may be composed of a plurality of layers of absorbant paper and/or a pad of absorbant fibers to absorb any liquid which seeps through the apertures in the artificial grass backing sheet." The Brazzell patent also recommends using a deodorizer after the animal has used the unit (deodorizer included with the unit at time of purchase). The purpose of the Brazzell absorbant layers is to hold the urine, encasing it between a bottom "impervious layer" and a top "nonabsorbant or impervious layer" of artificial grass. The trapment of the urine allows for bacteria to grow, causing odor. This bacteria growth prevents use of the pad for long periods of time.
While many additional patents could be cited regarding other variations of disposal systems, types of granular litter and containers none of systems of these patents have been found to overcome both the problem of odor and provide an easy, economical and convenient disposal and replacement. By way of contrast, U.S. Pat. No. 4,469,046 discloses and claims an effective means for handling the foregoing problems. However, due at least in part to the cost of producing a protective screen having the requisite characteristics, the protective screen is a major cost item in the system of the patent.